The long term goals of this project are to develop treatment strategies for X-linked myotubular myopathy (XLMTM). XLMTM is an X-linked, congenital myopathy characterized by profound weakness and hypotonia at birth. Typically affected males die prior to 1 year of age due to respiratory complications. The mutated gene, MTM1, encodes myotubularin, a lipid phosphatase, thought to be critical to muscle maintenance. Learning more about the gene expression profile of the disorder in humans and the MTM154 mouse model may identify potential pharmacologic targets. In Aim 1, the characterization of the gene expression profile in XLMTM human muscle and the MTM154 mouse will be performed using microarrays in order to identify disease-specific genes and non-specific alterations. In Aim 2, the microarray data will be verified by confirming transcriptional alterations at the protein level and to learn more about protein interactions by choosing a subset of uncharacterized transcripts to study. In Aim 3, cell therapy, using intra-arterial injections, a recently characterized and possibly more efficient mode of stem cell delivery, in the MTM184 mouse will be performed. This represents another strategy aimed at treating XLMTM by attempting to reconstitute myofibers lacking myotubularin expression. After the effectiveness of stem cell delivery to muscle tissue is confirmed, treated muscle will be tested for myotubularin expression, activity and immunolocalization. Microarrays will also be used to determine whether the introduction of functional myotubularin reverts the gene expression profile in the treated MTM154 mouse and important proteins and interactions confirmed in Aim 2 will be restudied. Once a variety of parameters are optimized, such as age of animal at treatment, type, number of and intervals at which stem cells are delivered, and the number of injections, the cell therapy experiments will enter a second phase where physiological parameters will be assessed in systemically treated animals. This project will introduce the candidate to a variety of new techniques such as microarrays, bioinformatics, stem cells and other experimental methods. This proposal affords him the opportunity work in an intellectually stimulating environment, were he will be required to think and approach scientific questions in novel ways fostering his transition to independence. Ultimately, the applicant would like to investigate the potential role of stem cells in treating neuromuscular disease and their general biology as a practicing neuropathologist in academia.